The present invention relates to an input-output device for a communication terminal equipment, and more particularly to an integrated input-output device for a data communication wherein a contact image sensor as an input unit and a printer as an output unit are integrated on a single circuit board.
Generally, a data communication terminal equipment includes an input device and an output device separately constructed from each other and available as separate units. Such a data communication terminal equipment further includes a transmission device for transmitting a signal from the input unit to a copy machine or a facsimile, and a device for applying an electrical signal to the output unit. These devices are also constructed as separate units. As a result, the overall construction of the data communication terminal equipment is complex.
The above-mentioned conventional input and output devices for the data communication terminal equipment will be described, in conjunction with FIGS. 1 to 4.
FIG. 1 is a perspective view of a conventional input device, for example, a read scanner. FIG. 2 is a sectional view of a contact image sensor equipped in the read scanner of FIG. 1. As shown in the drawings, the conventional input device comprises an optical output unit 2 for projecting light beams onto an original document 1, a lod lens array 3 for focusing the light beams reflected from the optical output unit 2 at different intensities depending on letters and characters on the original document 1, and an image sensing unit for sensing the reflected light beams fed through the lod lens unit 3 and converting them into electrical signals to be outputted.
In FIGS. 1 and 2, the reference numeral 4 denotes a sensor circuit board.
In operation of the input device having the above-mentioned construction, light beams emitted from the optical output unit 2 are projected onto the original document 1 and then reflected therefrom. The reflected light beams are then fed to the image sensing unit 5 through the lod lens unit 3 at different intensities depending on characters of the original document 1. The image sensing unit 5 converts the received optical signals into electrical signals having different current intensities determined by respective grayscale values of the characters and outputs them.
As shown in FIG. 2, the image sensing unit 5 comprises a photodiode region PD including a multilayered structure constituted by a transparent electrode 6, a semiconductor layer (a-Si:H) 8 and a low concentration p type semiconductor layer 9, and a thin film transistor region TFT including a multilayered structure constituted by a gate electrode 10, an insulating film 11, a semiconductor layer 12, an ohmic contact layer 13 and a source/drain electrode 14. The image sensing unit 5 further comprises a matrix wiring region L connected to the drain electrode of the thin film transistor region TFT and adapted to transmit a signal.
In this case, the low concentration p type semiconductor layer 9 of the photodiode region PD is connected to the source electrode of the thin film transistor region TFT.
In FIG. 2, the reference numerals 7 and 15 denote an insulating film and a metal electrode, respectively.
on the other hand, FIG. 3 is a sectional view of a conventional output device, for example, a thermal printer head. FIG. 4 is a sectional view of a heater of the thermal printer head of FIG. 3. FIG. 5 is a plan view illustrating a construction for connecting thermal printer heads to drive ICs.
As shown in FIG. 3, the thermal printer head as the conventional output device includes a heater 16 comprising a heater substrate 17 and a printed circuit board 19 both formed on a heat sink 20. The heater 16 is connected to a drive IC 18.
As shown in FIG. 4, the heater 16 is fabricated by coating a glaze layer 24 to a thickness of 800 to 1,500 .ANG. over the substrate 17 made of Al.sub.2 O.sub.3. Over the glaze layer 24, a resist film 23 is formed. Thereafter, a metal layer 22 made of Al is coated to a thickness of 1 .mu.m over the resist film 23. A selected portion of the metal layer 22 is then removed to form electrodes which are then subjected to an isolation treatment. A common electrode 21 is formed over one of the electrodes comprised of the metal layer 22. Over the entire exposed upper surface of the resulting structure, a passivation film 25 made of SiON is formed to a thickness of 4 .mu.m, thereby obtaining a heater. As a voltage is applied to both the common electrode 21 and the other electrode comprised of the metal layer 22, a heat is generated.
As shown in FIG. 5, the connection of thermal printer heads 26 to drive ICs 18 is achieved by directly connecting respective pads of thermal printer heads with corresponding pads of the drive ICs 18. For an original document of A.sub.4 size, 27 drive ICs 18 should be used so as to control the thermal printer heads 26 by blocks. In this case, the number of wires connecting the thermal printer head 26 with the drive ICs 18 is 1728 identical to the number of thermal printer heads 26 in a G.sub.3 200 pi facsimile.
In the G.sub.3 -grade facsimile, 1728 pixels are sequentially driven by the drive ICs 18 in 10 msec. In case of G.sub.4 -grade facsimiles, 3456 pixels can be driven in one msec. As a voltage of about several tens V, for example, 20 V is applied to each thermal printer head 26, a heat is generated from the heater of the thermal printer head 26. The heat is transferred to a heat-sensitive paper which is, in turn, discolored by the heat.
The discolored area of the heat-sensitive paper subjected to the heat appears black color so that it is distinguished from other areas subjected to no heat and appearing white color. In such a manner, characters and designs are duplicated on the heat-sensitive paper appears.
However, the conventional data communication terminal equipment is expensive and bulky because its input and output devices are constructed separately from each other. Moreover, this data communication terminal equipment has a limitation on development of a portable unit due to the bulky construction.